Puppies are a multi-billion Euro industry in Europe; 8 million puppies are purchased every year. But where are all these puppies coming from? For the first time, Our World unveils a criminal underworld of puppy traders trafficking dogs across Europe. From the illegal puppy mills in Hungary, the dogs are sold into a vast pet trade network in Western Europe. We follow a team of undercover vets and the charity Four Paws busting online puppy sales in Germany. We discover how pregnant dogs are being trafficked, and ultimately we see how the puppy mills are sending dogs to huge pet shops in Belgium, where they are bought by British gangs. Narrated by Stacey Dooley.